1. Field of the Invention
The present invention relates to a composition for an overcoat layer of an organophotoreceptor, an organophotoreceptor manufactured by employing the same and an electrophotographic imaging apparatus containing the same. More specifically, the invention relates to a composition for an overcoat layer suitable for use in an organophotoreceptor for liquid toner, the composition having good electrical properties and increased abrasion resistance and adhesion to extend the lifetime of an organophotoreceptor. The present invention also relates to an organophotoreceptor manufactured by employing the composition and an electrophotographic imaging apparatus containing the organophotoreceptor.
2. Description of the Related Art
In electrophotography, an organophotoreceptor has an electrically insulating photoconductive element on an electrically conductive substrate and may be in the form of a plate, disk, sheet, belt, drum or the like. An electrophotographic imaging process using the organophotoreceptor will now be described briefly.
First, the surface of an organophotoreceptor having an electrically conductive substrate where a charge transport material and charge generating material are provided is electrostatically charged, and then the charged surface is imagewise exposed to light. The light exposure selectively dissipates the charge in illuminated areas, thereby forming a pattern of charged and uncharged areas. Finally, a toner is then deposited on the surface to create a toner image on the surface of the substrate. The resulting toner image can be transferred to a suitable receiving surface such as paper. The imaging process may be repeated many times.
Both single layer and multilayer photoconductive elements have been used. In single layer embodiments, a charge transport material and charge generating material are combined with a polymeric binder and then deposited on the electrically conductive substrate. In multilayer embodiments, the charge transport material and charge generating material are in the form of separate layers, each of which can optionally be combined with a polymeric binder, deposited on the electrically conductive substrate. Two arrangements are possible. In one arrangement (the “dual layer” arrangement), the charge generating layer is deposited on the electrically conductive substrate and the charge transport layer is deposited on top of the charge generating layer. In an alternate arrangement (the “inverted dual layer” arrangement), the order of the charge transport layer and charge generating layer is reversed.
In both the single and multilayer photoconductive elements, the purpose of the charge generating material is to generate charge carriers (i.e., holes and/or electrons) upon exposure to light. The purpose of the charge transport compound is to accept at least one type of these charge carriers and transport them through the photosensitive layer in order to facilitate discharge of a surface charge on the photoconductive element.
An organophotoreceptor may be easily worn due to friction between toner and a roller or a cleaning blade, which decreases the thickness of the organophotoreceptor, resulting in a reduction in lifetime. To overcome this problem, an overcoat layer may be formed on the organophotoreceptor.
In recent years, there has been an increase in the development of electrophotographic printers using liquid toners, making it is necessary to develop organophotoreceptors for liquid toners. However, conventional overcoat layers have been proposed to extend the lifetime of an organophotoreceptor for dry toner. Therefore, there is still growing demand for overcoat layers that can extend the lifetime of an organophotoreceptor suitable for liquid toners, having improved electrical and mechanical properties.